Spraying metals or other materials



April 25, 1939. c. LUMB 2,155,948

SPRAYING METALS OR OTHER MATERIALS Filed July 23; 1937 P Pistol 5 v 4 INVENTOR ATTQRN EYS Patented Apr. 25, 1939 UNITED STATES PATENT OFFICE SPRAYING METALS OR OTHER MATERIALS Application July 23, 1937, Serial No. 155,321 In Great Britain August 18, 1936 1 Claim.

The invention relates to flame-spraying metallic material for the purpose of providing fin extensions formed of'such material upon a tube or other base. When it is desired to provide fins 5 upon a tube the methods hitherto adopted have consisted in either pre-forming the fins and 'soldering or welding them to the tube or forming the tubes and fins from a solid block of metal.

In certain 'cases the former process cannot be employed, as for example when tubes formed of certain aluminium alloys are employed, and the latter process is expensive when the employment of such metals is necessary or desirable.

According to the invention, in order to provide, 15 for example, circular fins upon a tube of metal,

glass or other material, the tube isinserted through an orifice in ablock of material to which sprayed metal willnot adhere, the surface of the block through which the tube projects being if 20 desired suitably formed so as to give the required shape of fin. The tube is allowed to project through the block to such an extent that when metal is sprayed on to the block as a matrix and the periphery of the tube the metal will adhere 25 to the latter and by continued spraying a fin will be built up which closely adheres to the tube.

In an actual example aluminum fins may thus be sprayed upon tubes formed from aluminium alloys or'other materials such as for instance 30 stainless steel, andsuch fins are so closely adherent to the supporting tube that they may be broken before the joint with the tube is affected. The fins may be formed as thin as desired, and for example may be one-sixteenth of an inch in thickness or they maybe thick at the base and thin at the outer edge.

In the accompanying drawing:

Figure 1 illustrates diagrammatically one mode of carrying out the invention, and' 40 Figure 2 .illustrates in like form a modified mode.

In carrying the invention into effect in one convenient manner .in' order to provide circular fins upon a metallic tube, and as illustrated in 45 Figure 1, the tube 'a is inserted through an orifice b in a. block c so as to project through the orifice the desired extent and form with a shallow recess dsurrounding the orifice an annulus into which the metal or alloy is sprayed, the

50 metal or alloy being directed against the periphery of. the tube, to which it adheres, and being built up within-the width of the annulus as the spraying operation proceeds. The block forms a temporary support for the fin and the surfaces 55 thereof upon which the metal or alloy is deposited are treated, as by greasing, so that while the sprayed metal or alloy will adhere to the tube it will not adhere to the block.

It will of course be understood that in order for the sprayed metal to adhere to the tube the 5 surface of the latter must be prepared for it, the customary preparation being by sand blasting. The surface must be perfectly clean andrough or at least microscopically rough as well understood in the industry.

During the spraying operation the spraying pistol will naturally be moved around the tube" so as to produce a fin of uniform thickness. If

desired the fins may quite easily be made of nonuniform thickness or may be arranged eccentri- 16 cally to the tube or made in corrugated form. Instead of circular fins, fins'of other shapes may quite simply be formed upon round tubes or upon tubes having other cross-sectional shapes.

In a modification a fin may be built up upon 20 an article by employing a sheet of material, for example glass or metal suitably treated on its surface so that the sprayed metal will not adhere thereto, this temporary support being shaped along its edge or edges so as to conform to the shape of the article to which the fin is to be applied, the temporary support being held against the article and the metal sprayed on to this support and on to the article so as to build up a fin or web of the required thickness and configuration.

Circular fins on tubes may also be made in this Way, the temporary support being as illustrated in Figure 2 in the form of a plate e having a semi-circular aperture j in one edge the 'diameter of which corresponds to the diameter of the tube a. By using such a support the fins. may be made to extend around a portion (as when the single plate e illustrated in full lines is eni-t ployed) or the whole (as when a second e shown 40 in dotted lines is also employed) of the periphery of the tube or other article.

Itwill be clear that many 'modificaflons may be made in the above embodiments withoii going outside the scope of the invention, which extends to the provision of fins or webs or the like of any suitable material upon articles of metal or other material.

It will be'clear thatthe invention findsone of its most important uses in the provision of fins of heat'radiating material upon articles which it is desired to cool and which are of material upon which it is ordinarily difiicult to obtain fins or like cooling surfaces. The invention may be applied, for example, to condenser tubes, air

cooled internal combustion engine cylinders or exhausts, oil tanks or sumps, but it is to be understood that these are only given by way of example and not of limitation.

I claim:

The method of forming an extension on an article, in the form of a thin projecting fin or flange, which comprises preparing the surface of .the article to which the fin is to be attached so 10 that the fin material will be adherent thereto, 

